Pump



May'2l, 1935. w. FERRls ET AL PUMP Filed March V13 1929 3 Sheets-Sheet 1 NK. mami vh E mgm@ M m T T MPREK, A

May 21, 1935.

w. FERRls i-r AL PUMP Filed March 13, 1929 5 Sheets-Sheet 2 Fl/5.5L.

INVENTORSI Jahw P FERR/s VWALTER FERR/s GEORGE #Fa/AN' ELE/f A. BENEDEK A TTORN E Y.

My 2l, 193.5. w. FERRE-s ETAL 2,001,957

r PUMP I ljilea March l15, y192, 3 sheets-sheet s F15. 5.' a 410 .evsk

iwi-Wg Bu ELE/r /f Enviar Patented May 1935 UNITED vSTATES PUMP Walter Ferris, John P. Ferri-s, George H, Foliiau,`

and Elek K. Benedek, Milwaukee, Wis.,

assignors to The Oilgear Company, Milwaukee, Wis., a corporation of Wisconsin Y Application Maren 13, 192s, serial N0.346,1o,4

7 claims.

This invention relates to hydraulic pumps and motors of the high speed, multiple piston type. For ease of explanation the machine hereinafter described will be referred to as a pump al- 5 though it functions satisfactorily as a motor, and. in fact, some of the novel featur thereof have particular utility when functioning as such.

Pumps of this type are ordinarily operated continuously at constant speeds in excess of six hundred revolutions per minute, -and are commonly called upon to deliver liquid at pressures in excess of one thousand pounds per square inch. Although in some instances they receive their entire Vsupply of liquid at substantially .atmos-H pheric pressure from appropriate reservoirs, such pumps are more frequently so connected with the power transmission circuit as to receive their supl ply of 'liquid directly from the return side of the circuit. In some circuits, commonly known as differential circuits, there is a difference between the rate of flow in the working side and the rate of flow in the return side of the circuit, so that the demand of the pumpis sometimes greater and sometimes l'ess than the supply actually furnished by the return side. Provision is ordinarily made, in installations involving differential circuits; for supplying liquid to the pump from an auxiliary source to make up for any deficiencies in-the supply from the return side of the circuit,`

and also for permitting the escape of any excess liquid within the return side.

'I'his is usually due to the use of .a .motor which has greater volumetric capacity when operating in one direction than in the other. The ordinary press cylinder and piston with a rod on one side only isl such a motor. In many hydraulic presses this piston rod is made very large with the object of reducing the cylinder volume in the rod end to obtain a fast movement of the piston during the return stroke, using only the same flow of working fluid which imparts a slow movement on the working stroke. l

With a piston rod -which occupies one-hal! of the total cylinder volume, the return stroke will 4J be twice as fast as the working stroke for the same: rate of ow from the pump. During the working `stroke the flow of the pump operates on the full area of the piston, while the piston movement is only expelling from the rod end of the cylinder an amount equal to one-'half of this pump flow. The other half must be obtained from an auxiliary supply usually kept in reserve in a sump or oilpot.

During the return stroke lthe full ilow of the pump is delivered to the rod end and acts on only (Cl. ID3-161) .of this oil and the other half must be discharged 5 into a reserve supply or sump.

When excess oil is to be discharged into the sump, it is not essential to have especially large passages thru which it may iiow, as the full pressure of the pump is available on the rod end of l the piston to force the'return oil out of the head .end of the cylinder. But when the returning oil is less than the amount discharged by the pump,

there is no force available to raise the deciency from the sump orreservolr and into the filling l pumpcylinders, except the suction force due to atmospheric pressure. This makes it necessary to have large and direct passages to raise this make-up oil from the sump to the intake side of. the pump without passing it thru the restricted passages which are used to conveythe oil to the external circuit connectio'ns'as hereinafter described.

At the high speeds commonly employed the problem of'illling each of the several pump cylin- 25 ders within the exceedingly brief period allowed '(ordinarily less than one twentieth of a second) is most serious even under the most favorable operating conditions. In pumps heretoforedesigned complete illling is impossible and in instances involving high differential (where the rate of liquid supply from-the return side of the circuit is considerably less than the demands of the pump) such pumps have been known to run only 80% full. This failure to effect complete 35 lling not 'only reduces the volumetric efilciency `of the pump, but experiments show that it is also Athe primary causeof objectionable pump noise.

One object of the present invention is to increase the volumetric emciency in pumps of the 40 type mentioned. This is accomplished by a novel design and arrangement of'ports and passages which afford, as near as practicable, a direct ow of liquid to the several pump cylinders, `with a minimum resistance to such now. The design hereinafter described is the resultoi! extended experimentation and pumps embodying that de- Sisn have demonstrated a volumetric eillciency of 96%.

Another object is to reduce pump noise. This is accomplished in part as a consequence of the improved filling although we have discovered 4that part of the noise is due to the abrupt changes in pressure within each cylinder caused by the instantaneous exposure thereof to the high pressures in the working side and to the low pressures in the return side of the circuit, alternately. This difliculty is overcome by a design of ports which render these pressure changes less abrupt.

Another object is the provision in a pump or motor of improved means eiecting a hydraulic counter-thrust between pintle and cylinder barrel on the side of pintle opposite to the discharge port. The purpose of this thrust is to counteract a combined mechanical and hydraulic thrust produced by the linward reaction of the pump pistons upon the cylinder barrel (tending to press it against the pintle) and the pressure of the oil -in the discharge port`which is forced out in a film between the adjacent. surfaces of cylinder barrel and pintle in the neighborhood of the port edges. This film pressuretends to lift the cylinder barrel away from contact with the pintle, and is in general greater than the piston pressures which force the cylinder barrel toward the pintle. Attemptsheretofore made to supply the necessary hydraulic balancing force to maintain close contact of cylinder barrel against pintle on the pressure side have been carried out by the use of balancing ports extending lonly part way around vthe pintle and forming pockets which accumulate foreign matter and ultimately discharge it 'between the wiping surface with disastrous results.

Other objects and advantages will appear from the following description of an illustrative embodiment of the present invention.

In the drawings:-

Figure 1 is a sectional view of a pump embodying the several novel features of the present invention.

Fig. 2 is a sectional view taken in a right angles to that of Figure 1.

Fig. 3 is an axial sectional view of the pump cylinder barrel applied to one end of the pintle.

Fig. 4 is a sectional view-on the line 4-4 of Figure 3.

Fig. 5 is a sectional view of the other end of the pintle and taken substantially on the line 5 5 of Figure 2.

Fig. 6 is a sectional view of one of the two-inplane at take valves shown in Figures 1 and 2.

The pump shown is of the type described in the patent to Walter Ferris, No. 1,558,002,2issued October 20, 1925. It is supported and housed within an appropriate casing I0 having a hollow base I I laterally extended to form a liquid reser` v oir I2 of ample capacity. It comprises an impelling means of a well known type including a rotary cage I3, fixed to the end of a drive shaft I4 and journaled on xed anti-friction bearings |5,vthe cage coacting with a rotary cylinder barrel I6, mounted on one end I1 of a pintlek I8, to effect reciprocation of the several radial pistons |9 disposed therebetween. Each piston reciprocates within a cylinder bore 20 in the barrel I6 so as to cause liquid to enter and leave the bore through an appropriate port 2|. During rotation of the cylinder barrel upon the pintle end I1, each of the several cylinder ports 2| register alternately with upper and lower ports 22 and 23 formed in the pintle. In this instance the ports 22 and 23 constitute transverse gashes formed in the upper and lower faces of the pintle which communicate, respectively, with upper and lower longitudinal passages 24 and 25 in the pintle. In this instance one end of the base 26 of each gash is acutely bevelled as at 21 so as to substantially merge with` the cylindrical surface of the pintleA (see Fig. 4) for a purpose which will hereinafter appear.

'I'he other end 28 ofthe pintle I8 is anchored in an upright arm 29 rockably supported at its lower end upon a shaft 30. One end of shaft 30 is fixed in a lug 3|, constituting anl integral part of the rear wall of the casing lli, while the other end `is xed inv a cylindrical block 32, removably iixed to the front Wall of the casing. A large passage 33 (Fig. 2) in the rock arm 29 communicates with the lower pintle passage 25 through a tapered pintle passage 34, which, as indicated in Figure 5, is inclined with respect to the passage 25. A plug 35, inserted in and closing the end of the passage 25, is providedwith a bevelled end 36 disposed substantially flush with-the passage 34 and so inclined as to assist in bending the column of liquid in its iiow between the passages 33 and 25. A second large passage 31 (Fig. 2) communicates with the upper pintle passage 24 through a similarly tapered and inclined passage 38 (Fig. l) in the pintle, a similar plug 39 (Fig. 5) having a bevelled end 40 which serves in a similar manner to bend the column of liquid owing between passages 31 and 24.A .A large pipe 4I, whose lower end is submerged in the body of liquid inthe reservoir I2, isflxed to the lower end of the arm 29 and communicates with the passage 33, and a second pipe 42, similarly mounted,lcommunicates with the passage 31. 'Ihe arrangement is such as to permit a direct and easy iiow of. liquid from the reservoir I2 to either of the pintle passages 24 or 25.

Each of the pipes 4| and 42 is provided with an inwardly opening check valve 43 of ample size and preferablyso designed as to oier a minimum resistance to admission of liquid thereto. One of these valves is shown in section in Figure 6. It comprises a casing 44 xed to the end ofthe pipe and having a substantially bell shaped mouth portion 45 containing anupwardly converging inlet opening 46. A hollow cup -shaped valve element 41, seated over the opening 46, is provided with an annular bevelled face -48 for coacting with an appropriate valve seat 49 to normally close the opening. Tail pieces 50 depending from the element 41 into the opening, and narrow guide webs 5| in the housing serve as centering means for the valve. L ugs 52 depending from the pipe limit the upward movement of the valve element so as to insure a free flow of liquid around the valve element and into the pipe when' the valve is elevated. It will be noted that the check valves 43 prevent the escape Vof liquid from either of the pipes to the reservoir |2-.

A pair of longitudinal passages 53 in the shaft 3|) communicate with one side of'. a hydraulic power transmission circuit (not shown)v through a port 54 (Fig. 1) in the forward end of the shaft, and a second pair of passages 55 communicate with the other side of the circuit in a similar manner. Passages 53 also communicatewith passage 31 in the rock arm 29 through a port 56 in the shaft and an upwardly inclined passage 51 in the arm (see Figs. 1 and 2); and passages 55 communicate with passage 33 in the arm through a similar port 58 and passage 59. Thus ywhen the several pump cylinders discharge into the upper pintle passage 24 this entire discharge isdirected through passages 31, 51A and 53 into one side of the circuit, the liquid returning from the other side of the circuit being directed through passages 55, 59, 33 to the lower pintle passage 25 and then back to the pump cylinders. When the'pump is re- `jfersed the course of the Il oW is the same except in the reverse direction, liquid from the return side of the circuit beingdirected tothe pump cylinders through the passages 53, 51. 31 and 24.

' In either case' the entire pump discharge ows downward through .passage 31 or 33 and 51 or 59,A respectively, in the rock arm, and vthence through port 56 or 58 and the relatively constricted passages 53 or 55 inthe shaft 30.` The 'return flow from'the motor, which, as already from the available discharge pressure of 1000#4 per square inch.- `:But if the return flow is less than the pump discharge, the vdeficiency must be raised from the sump by the intake suction of the pump. In previous designs this was eiIected through lan intake check valve formed in the valve casing 18, and the make-up 'oil had to pass up through the restricted passages 69, 68 or 10,

' and 55 or 53, the only force available for overwhich also has to overcome coming-.the resistance being the intake vacuum allpintle and cylinder port losses. i

As indicated in Figure 2 the passages 59 and 51 are preferably acutely disposed with respect to the passages 33 and 31, respectively, so that the liquid returning from the return side of the circuit through either of them and discharging at high velocity therefrom into one or the other of the passages 33 and 31 will produce an injector.

action therein tending to induce an upward ow of liquid through the associated pipe 4| or 42. This action assists the pump pistons'in lifting liquid from the reservoir l2 in such quantities as to make up for any deciency in the supply from the 'return side of thev circuit and thereby effect complete filling ofthe pump cylinders.

It will of course be understood that the Ipump is driven'at constant speed in one direction only through the shaft I4 and that the flow is reversed and regulated in a well known manner by lrocking the arm 29 upon the shaft 30. In the pump shown this is accomplished by action of a l plunger mechanism 60, similar to that disclom in the patent above ident-ined, operatively connected, as at 6|, to the upper end of the arm.

Provision is made in the pump shown for permitting liquid to escape from the return side of the` circuit in the event that that supply is in excess of that required to illl the pump cylinders. Themechanism for this purpose comprises a shuttle valve 62, similar to the one described in the above entitled patent. in a casing'63 xed to the lower end of the rock arm 29 between the pipes 4| and 42. This casing contains a cylindrical bore having three spaced annular grooves 65, 66, and 61 formed in the wall thereof. Groove 65 communicates with passages 55 through a passage 68; groove 66 communicates with a discharge pipe 69; and groove 51 communicates with passage 53 through a passage 10. One end 1| of the bore communicates with the passage 68 through a passage 12 and the other end 13 of the bore communicates with the passage through a passage 14. A piston valve having three spaced heads 15, 16 and 11 is closely This valve is housed iltted for lengthwise reciprocation in the bore. 'I'he lower end of the pipe 69 carries a spring loaded check valve 18 which permits liquid to escape from the pipe to the reservoir I2 whenever the pressure therein is suilicient to lift the valve element 19 thereof against the pressure of the spring 88.

'Ihe arrangement is such that when the piston valve is in the intermediate position shown in Figure 1 the central head 16 thereofcovers the intermediate groove 66. When the pump is discharging liquid under pressure through the passages 33, 59 and 55 into therworking side of the circuit this pressure is transmitted through the passages 68 and 12 `to the right end 1| of the bore, causing the valve element to shift to the left and thereby opencommunication between rg'ooves 66 and 61, so that the passages 53, com- .municating with the return side of the circuit, vare then open to the pipe 69 and liquid from the return side, inexcess of that required to fill the pump cylinders, may escape through the valve 18. Similarly, when the pump is discharging through passages 31, 51 and 5.3 into what is then the working side of the circuitthe valve element is shifted toward the right under the pressure transmitted to the end 13 of the valve bore `through passages 14 and 10, so that any excess liquid is free to escape from the then return side of the circuit through the passage 68, grooves 65 and 66, pipe 69 and valve 18. It will thus be noted that when theV liquid supplied from the return side of the circuit is in excess of that required by the pump the pressure within the return side is 4determined by the tension in the spring 80 of the check valve 18. This may be varied by appropriate adjustment of the hollow plug 8| which is screwed into the valve casing and incidentally forms an outlet therefor.

Referring now to Figures 3 and 4 letit be assumecl that the cylinder barrel |6 is rotating clockwise (Fig. 4) and that the pintler I1 has been shifted toward the left so that the pistons I9 in the lower half of -their circular travel, are forcing liquid under pressure from the cylinders into'the llowerv pintle port 23 and passage 25 and, in the upper half of their circular travel, liquid returning from the return or low pressure .side of the circuit is flowing intothe cylinders.

Under this condition of operation, the cylinder barrel imposes a downward thrust upon the pintle, due to the aggregate or resultant thrust of the several pistons, which in this instance is upward. but which is more than overcome by the downward thrust imposed by the liquid under pressure in the port 23 and by the liquid which has escaped outwardly from and around this port into the running t between cylinder barrel and pintle and tending to separate them. This unbalanced thrust tends to increase the working 'following manner.

Two pairs of grooves 82-83 and 84-85 are formed about the pintle, the grooves of each pair being equally spaced from the central plane of rotation of the cylinder barrel. Each of these than the lower half and the lower half of eachk groove 84 and 85 of the other pair being wider than the upper half. (See Fig. 3.) Grooves 84 and 85 communicate with the upper pintle port 22 through a drilled passage 86 and grooves 82 and 83 communicate with the lower pintle port 23 through a drilled passage 81. Thus when the lower pintle port and the cylinders in the lower half of the circle are exposed to the high pressure side of the circuit this .pressure is transmitted through passage 81 to the grooves 82 and 83, and by reason of the fact that these grooves are wider at the top than at the bottom, the hydraulic pressure therein produces a resultant upward thrust against the cylinder barrel to coun' teract the unbalanced' thrust hereinabove described, and the cylinder barrel is thus malntained concentric with respect to the pintleA with a uniform working clearance all around. When the pump is reversed so that the upper pintle port 22 and the cylinders in the upper-half of the circle are exposed to high pressure, this pressure is transmitted to the grooves 84 and 85 and a similar hydraulic thrust is produced which tends to force the cylinder barrel down upon the pintle to thereby counteract the unbalanced up ward thrust upon the cylinder barrel which normally exists under that condition of operation.

By the use of endless grooves which completely encircle the pintle we avoid the formation of shoulders or faces which might tend to pick up or accumulate dirt or sediment contained in the hydraulic medium. In order to rid them of any such matter however we provide additional grooves 88 in the interior of the cylinder barrel into which such matter is thrown, by the centrifugal force resulting from the rapid rotation of the cylinder barrel. Discharge passages 89 leading from these grooves communicate with lengths' of tubing 90 of suflicient length to resist the flow of liquid in any appreciable quantity therethrough but of suiicient diameter to carry olf the very fine particles which may be contained in the grooves. This tubing is shown wrapped about the hubs of the cylinder barrel.

In pumps of this type oil is ordinarily used as the hydraulicpower transmitting medium because of its lubricating qualities, and the normal leakage between pintle and cylinder barrel is commonly relied upon to effect lubrication of those parts. Throughout limited areas bordering that pintle port22 or 23 in which the oil is exposed to high pressure the lubrication is good but lubrication of other areas is more or less im'- perfect. In the pump shown provision is made for effecting a better and more uniform spread of the oil film between pintle and cylinder barrel. To this end two pairs of blindvgrooves 9I-92 and 93-94 having no outlets are formed inthe interior of ,the cylinder barrel completely encircling the pintle. Grooves 9| and 92 are equally spaced from and at opposite lsides of the pintle ports 22 and 23, and grooves 93 and 94 are equally spaced from and beyond the grooves 9| and 92, respectively. Oil from that port 22 or 23 exposed to high pressure works its way lengthwise of the pintle and enters the grooves 9| and 92 establishing a pressure therein which is substantially uniform through the periphery thereof. These grooves then act as high pressure distributing mains from which the oil works in both directions along the pintle to form an oil film over the entire area of the pintle comprised part of the area. But when it enters the secondA pair of grooves 93 and 94 a uniform pressure throughout the periphery Vthereof is immediately established. 'Ihese grooves then, acting as distributing mains, cooperate with the grooves 9| and 92 to provide a substantially uniform oil film over the pintle areas comprised therebetween. They also function in a similar manner to spread an oil lm over those pintle areas comprised between them and the grooves 84 and 95. Grooves 84 and 85, beside their special balancing function already described, act f as lm re-distributing grooves in the same manner as grooves' 9|, 92, 93 and 94, already described.

As hereinabove pointed out one end of the base 26 of each of the gashes 22 and 23, constituting the upper and lower pintle ports, is bevelled off sharply, as indicated at 21 in Figure 4. This is for a purpose which will now be described. Let it again be assumedthat the cylinder barrel is rotating clockwise and that the -pintle 'has been shifted toward the left, as indicated in Figure 4, so that the several pistons in the lower half of their circular travel. are executing a working stroke and in the upper half a suction stroke.

Thus throughout the lower half of its circular travel, each piston and parts connected therewith are exposed to the high pressure (sometimes about fteen hundred pounds per square inch) in the lower pintle port 23, and during the upper half -of this travel each piston and connected 'parts are practically unloaded due to the low pressure (sometimes less than atmospheric pressure) in the upper pintle port 22. The bevelled portions' 21 provide a tapered end for each pintle port by which the change from full load to no loa-d, and vice versa, upon each piston, as 4it passes through each dead center position between the upper and lower halves of its circular travel, is rendered less abrupt, thus reducing the shock and the resulting noise as each cylinder full of low pressure oil is suddenly exposed to the oil in a high pressure port. For instance that piston and cylinder in horizontal position at the right of the pintle in Figure 4 is in dead center position, and having just completed a suction stroke there is practically no load thereon. Then as the cylinder barrel continues to rotate clockwise the port 2l thereof is gradually opened to the high pressure in the port 23 through the tapered end thereof, formed by the shallow gash 21, and the building up'of pressure in the cylinder is obviously less abrupt than if the port were instantly opened by a square ended port. Similarly as each piston and cylinder passes through the other dead center position at the end of a working stroke, it remains under full pressure until the port 2| thereof is gradually opened to the low pressure port 22 through the tapered end thereof formed by the shallow gash 21. Again the transition from full load to no load is rendered less abrupt by reason of the tapered end of port 22, the compressed oil expanding gradually through the grooves and thus softening the noise, which results from a sudden expansion of a cylinder partly full of compressed oil and brought in communication with the low pressure port.

Various changes may be made in the embodiment of the invention` hereinabove described without departing from or sacrificing any of the advantages of the invention as deilned in the appended claims.

l. In a reversible ow hydraulic pump the combination of a pintle, liquid impellingmeans rotatable thereon, intake and dischargepassages in said pintle communicating with said impelling' means, circulating passages fed from said pintle passages, a liquid supply source, conduits of a l capacity not materially less than said pintle passages forming direct communications between said source and said pintle passages, respectively, and large capacity check valves permitting a free iiow of liquid through said conduits from said source.

2. In a'hydraulic pump the combination of a pintle, liquid impelling means rotatable thereon, intake and discharge passages in said pintle communicating with said impelling means, a liquid reservoir, a large conduit of a capacity not materially less than said pintle passages connecting said reservoir with said intake passage, a valve casing at the lower end of said conduit, said casing having an outwardly aring inlet opening submerged within the body of liquid in said reservoir, and a hollow valve cooperating with said opening to freely admit liquid to saidcasing but preventing escape of liquid therefrom to said reservoir.

3. In a hydraulic pump the combination of a pintle, liquid impelling means rotatable thereon, intake anddischarge passages in said pintle communicating with said impelling means, a support 'for said pintle, passages in saidv support communicating, respectively, with said pintle passages through the sides of said pintle, and plugs in the ends of said pintle passages, said plugs having bevelled ends forming deectors for the uid passing between said pintle passages and support passages.

4. In a reversible ilow hydraulic pump the combination of a pintle, liquid impelling means rotatable thereon, interchangeable intake and discharge passages in said pintle communicating with said impelling means, liquid supply conduits leading to said pintle 1 es, respectively, check valves in said conduits, circulating comat opposite sides of said ports and communicat ing with one of said passages, and a second pair of reversely tapered grooves encircling said pintle at opposite sides of said ports and communicating with the other of said passages.

-6. In a hydraulic pump or motor the combination of a pintle, liquid impelling means rotatable thereon, passages in said pintle communicating with said impelling means, a groove encircling said pintle and communicating with one of said passages, and means permitting the escape of foreign matter from said groove, said means comprising a coil of small diameter tubing carried by said impelling means and communicating with said groove, the length of said tubing being such as to effectively resist the escape of liquid in any considerable quantities from said groove.

7. In a hydraulic pump or motor the combination of a pintle, liquid impelling means including an element rotatable on said pintle, passages in said pintle communicating with said impelling means, a groove in said element encircling said pintle and receiving working fluid from one of said passages and adapted by centrifugal action to eilect precipitation of foreign matter contained in the fluid therein and a constricted vent for said groove through which foreign matter is removed by the restricted ilow of working fluid therethrough.

WALTER FERRIS. JOHN P. FERRIS. GEORGE H. FOBIAN. ELEK K. BENEDEK. 

